1. Field of the Invention
The present invention generally relates to tubular conduit of the type that might be employed for the housing of underground cables, such as fiber optic cable, coaxial cable, or the like. More particularly, the present invention relates to a partioning device that may be inserted into such a conduit such that the conduit is divided into separate chambers or cells and a method of manufacturing such a device.
Cable, such as fiber optic communication cable, is often buried underground in great lengths. It is known in the art to bury the cable in the ground so that the area above ground is not cluttered with the cable and its respective support apparatus. Furthermore, by positioning the cable underground, it is more protected from the weather and other potentially damaging circumstances.
It is also known in the cable art to position the cable within a conduit in order to more fully protect the cable in the ground. The conduit is often formed from lengths of polyvinyl chloride tubing or the like, which is laid in the ground. A rope is then blown through the conduit, and the rope in turn is attached to one end of the cable. By pulling the rope, the cable is drawn through the conduit. Once in place within the conduit, the cable is protected from damage that may be caused by weather, water and the like.
It has been found that certain rodents will sometimes gnaw through an underground conduit. Hence, much underground conduit is employed which has a diameter of two inches or more, which is large enough to impede damage from most rodents. While such conduit provides excellent protection for cable, there is also much unused or xe2x80x9cdeadxe2x80x9d space within such a conduit. With the advent of fiber optic cables, which may be only a half-inch or less in diameter, the majority of the cross-sectional area of the average conduit is dead space.
After a conduit is in place, it may be subsequently desired to run a second cable through the conduit. As such, it would be desirable from a cost and time standpoint to make use of the dead space within an existing conduit, rather than lay a new length of conduit. However, it has been found that it is difficult to merely insert a second cable into a conduit that already contains a first cable. When a rope is blown into a conduit already containing a cable, or a second cable is xe2x80x9csnakedxe2x80x9d through the conduit, they are often impeded by the first cable, making it impossible to insert the second cable.
There exists a product that overcomes some of the above-mentioned obstacles. A single sleeved innerduct structure includes a pair of adjacent strip-shaped layers of flexible textile material that are joined along their longitudinal edges to define a channel through which the cable can extend longitudinally through the innerduct structure between the layers. The adjacent layers have differing widths between their longitudinal edges, whereby the wider layer bulges away from the narrower layer to impart an open configuration to the channel. A need exists, therefore, for a method of inexpensively and efficiently manufacturing such a flexible conduit partition device. Further, in some applications it is desirable to provide a multi-sleeved conduit partition device, where each sleeve includes a plurality of cells for receiving cables and the like.
2. Description of the Prior Art
All patents cited herein are incorporated by reference in their entirety.
U.S. Pat. No. 5,587,115, issued to Allen, is directed to a method of manufacturing a conduit assembly with a floating divider by extruding a casing through a die while at the same time feeding a web member into the casing as it is being extruded to form a plurality of chambers. If the conduit assembly is manufactured with a line, such as a rope or a cable, the rope and/or cable is likewise fed into the casing adjacent to the web member into one or both of the chambers.
U.S. Pat. No. 4,836,968, issued to Cakmakci, is directed to a method of making a fiber optic duct insert by continuously extruding plastic material into a multi-chambered conduit insert including at least two spaced apart longitudinally extending substantially parallel first and second chambers. The cross-sectional configuration of each of the chambers is defined by generally parallel inner and outer side walls joined at one edge thereof by a base wall and joined in an opposite edge thereof by a top wall. A hinge portion connects adjacent edges of the inner walls and the base walls of the chambers together. Opposite ends of the inner walls are spaced farther apart than the adjacent ends of the inner walls in order to expose the exterior surfaces of the inner walls to a cooling medium during the manufacturing process.
U.S. Pat. No. 4,582,093, issued to Hubbard, discloses a method of making a fiber optic duct insert by utilizing a plastic extrusion process to produce a multi-chambered conduit insert which can be utilized to convert a single chambered conduit into a multi-chambered conduit. In particular, the conduit insert includes a plurality of cooperating longitudinally extending walls having curved outer surface portions and defining a plurality of parallel spaced apart coextensive chambers. In the preferred embodiment of the invention, two identical conduit inserts are disposed in back-to-back relationship and form an insert assembly for insertion into the single chambered conduit.
Other patents that demonstrate the state of the art with respect devices that facilitate the placement of multiple cables within a single conduit are as follows:
One problem associated with many of these devices is that they are mostly extruded plastic products, which do not bend or twist very well. It is difficult to force a semi-rigid, plastic structure into a rigid pipe or tube, particularly one that already contains a cable. Also, the speed of installation of the rigid divider is severely limited by the heat and resistance caused by friction. A flexible, multi-celled textile sleeve conduit overcomes the above problems, and a method for efficiently and inexpensively manufacturing the product is thus desired. Further, a multi-sleeved conduit containing a plurality of cells per sleeve is desirable for receiving a larger bundle of cables, as well as a method for making such a device.
Accordingly, it is an important object of the present invention to provide a method for efficiently and inexpensively manufacturing a flexible, multi-celled innerduct structure for fiber optic cables, coaxial cables, and the like.
It is another important object of the present invention to provide a method for manufacturing a flexible innerduct structure having a pull cord or tape inserted and slidably disposed therein during the manufacturing process.
Yet another important object of the present invention is to provide a series of flexible, multi-celled innerduct sleeve structures in a parallel configuration, so that each sleeve structure may be individually separated from the others, or combinations of two or three (or more) sleeves may remain in parallel configurations for desired applications, as well as a method for manufacturing such a device.
Still another important object of the present invention is to provide an automated method for manufacturing a flexible, multi-celled cable conduit structure that is biased toward an expanded passageway configuration, but is also collapsible in a rolled up configuration.
Another important object of the present invention is to provide a flexible, multi-celled cable conduit structure and a method for commercially manufacturing the same, which overcomes some of the problems associated with other multi-chambered conduit structures and their methods of manufacture.